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Enhanced upper stratospheric HNO3 during Antarctic winter 2003 and Arctic winter 2003/2004

Gabriele P. Stiller(1), Thomas von Clarmann(1), Herbert Fischer(1), Bernd Funke(2), Gizaw Mengistu Tsidu(1,3), Norbert Glatthor(1), Udo Grabowski(1), Michael Höpfner(1), Sylvia Kellmann(1), Michael Kiefer(1), Andrea Linden(1), Mathias Milz(1), Tilman Steck(1), Ding-Yi Yang(1,5), Manuel López-Puertas(2) and J. Steinwagner(4)

(1) Forschungszentrum / University Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany
(2) Instituto de Astrofísica de Andalucía, Apartado Postal 3004, 18080 Granada, Spain
(3) University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
(4) Max-Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
(5) SAIC/GSO, 7501 Forbes Blvd, Seabrook, Maryland 20706, United States


Vertical profiles of stratospheric HNO3 were retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the Envisat research satellite during the Antarctic winter 2003. A high second maximum of HNO3 was found around 34 km altitude with abundances up to 14 ppbv HNO3 during July. Similar high abundances had not been reported in the literature for previous winters, but for the subsequent Arctic winter 2003/2004, after severe perturbations due to solar proton events. The second HNO3 maximum in the Antarctic stratosphere started to develop in early June 2003, reached peak values during July 2003, and decreased to about 7 ppbv by the end of August while being continuously transported downwards before finally forming a single HNO3 layer over all latitudes in the lower stratosphere together with the out-of-vortex primary HNO3 maximum. The HNO3 decrease in August 2003 was correlated with photochemical build-up of other NOy species as ClONO2 and NOx. From the time scales observed, it can be ruled out that the 2003 long-term HNO3 enhancements were caused by local gas-phase reactions immediately after the solar proton event on 29 May 2003. Instead, HNO3 was produced by ion cluster chemistry reactions and/or heterogeneous reactions on sulfate aerosols via N2O5 from high amounts of NOx being continuously transported downwards from the lower thermosphere during May to August. By comparing the evolution of the second upper stratospheric HNO3 maxima in the Antarctic winter 2003 and the Arctic winter 2003/2004, we conclude that it is likely that similar production processes took place during both winters.

The IMK/IAA MIPAS-ENVISAT TEAM is: T. von Clarmann (1), H. Fischer (1), B. Funke (2), Gizaw Mengistu Tsidu (1,3), N. Glatthor (1), U. Grabowski (1), M. Höpfner (1), S. Kellmann (1), M. Kiefer (1), A. Linden (1), M. López-Puertas (2), M. Milz (1), T. Steck (1), G.P. Stiller (1)

(1) Forschungszentrum Karlsruhe/University of Karlsruhe, Institut fuer Meteorologie und Klimaforschung, Karlsruhe, Germany; (2) Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain; (3) now with: Institute of Environmental Physics, University of Bremen, Bremen, Germany


Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry